Telephone-exchange system.



T. G. MARTIN. TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED JUNE 1e, 1906V RENBWBD MAR. 1,109,650.

T. G. MARTIN. TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED JUNE 16,1906V Rmmwm MAR.

T. G. MARTIN. TELEPHONE EXCHANGE SYSTEM. APPLmATIoN FILED JUNE 16.1906 RENBWBD MAR.

A mi 1m Lm ls t, ps emi du es +07 D e. Llv na D1 @wm www O. 6 'I 9 O 1 V2 1 j 72 I yofmw T. G. MARTIN. TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED JUNE 16,1906 RENEWBD MAR.27, 1907. 1,109,650.

Patented Sept. 1, 1914.

'7 SHEETS-SHEET 4.

T. G. MARTIN.

BONE EXCHANGE SYSTEM.

TELEP uATloN MLU 315mm 1900 BENLWED MAM 27. 1907.

Patented Sept. 1, 19M.

7 SHEETSSHEET .f1

T. G. MARTIN.

TELEPHQNE EXCHANGE SYSTEM.

APPLICATION FILED JUNE1G,19OG RENBWED MAR. 27, 190'?. 1,109,650, Patented Sept. 1,1914l .m f nunf, E I 70, ,Dunn E fw wnnnn a w n f 3D3) 9 9 f Y D D l l T. G. MARTIN.

TELEPHONE EXUHANGE SYSTEM.

APLk`A'I`0N TLED JUNE 10, 10U@ VJJNLV/'ED MAR. 27` 29C?. y 09,650' Patented Sept. 17 1914,

n 7 SHEETSWSHEET 7,

UNITED PATENT @F.Ftliil.

TALBOT G. MARTIN, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ,ASSTGI' FIRST TRUST AND SAVINGS BANK, TRUSTEE, OF CHICAGO, LLINI..

TELEPHONE-EXCHANGE SYSTEM.

Application filed .Tune 16, 1906, Serial No. 322,079.

Specification of Letters Patent.

lfatontiil. Smit. i?) 3,4.. Renewed March 27T 1307. Serial No. 364,754..

To (17". y11i/mm. it 77mg/ Cannara.:

lu` it known that l, TALBOT (lr. MARTIN, a itifcnu ot tho llnitvil States of Amarina, and rwiilcut` ot Chicago, .("ook county, Illinoin, have iuvvntiil a Certain new and useful 11nprovi-niont in Tel@phone-Exchange Systems, of \vhi h the following is a S}w ilication.

lily inrontion relatos to telephone systems in `goncral, hut more particularly to autoinatio or semi-automatic telephone exchange ,svstonm anil @specially to systems in which the current for hoth talking and svvitthing purposes is Supplioil to tlux tolvphone linesI troni a ('oinnion hattorv or other centralized source ot' supply locatml at thvy exrhango or @mitral Station.

In vortaiu rosperts my proaent invention if; in the nature of an in'iprovouiont on the Sys tuin and apparatus,` dist-losod in my prior ap plu-ation Serial No. 319,255 tiled hy nl@y in they llnitml States latint Oliice on the 29th ,dav of May, 1906.

(ivnurally srtatoil tht` ohjvct of my present invc-ntion is thex provision of an improved sind highli7 @tirivnt tolcphon(x system involvinf`Y improvtd apparatus for trunhing in op pofiitfdireftions over oner and tho mino truulclino.

Special ohiot'ts of my invention aro thoy provision ot two-wav trunks in roinhination with a oounnon hattorv or other Suitahlc runtralizil noni-oe oi talking and uw'itihing vin-ront; th(l provision of autmnatii. mean*y tor autoinatirally trunking in oney dirortion ovflr two-Way trunlvline, in combination with separate and distinct autonlatic moan tor trunkingr in the opposite direction over Quid line; the provision of tivowif'ay trunks @noli 'jiu'oviilotl at its oppositey muis with r0- p Yatom and scloctor, tho selovtorS and 1'0- poatilrs lining distinct and separato `from oath other, the repeater at ono 0nd lining fulaptwl to colierato with the solortor at the other mid for trunking over the lin@A in ono (liroftion, aiul the othvr ropeattr and selortor heilig adapted to copcrate with nach othcr in automatically trunking over theline in th(l oppositv ilircf'tion; and the provifiion of Certain details and features of in'iprovonimit, together with certain novel Circuitv arrangenwnts and Con'ihinationS tonding to inrfrvasc the general ollicivnov of a telephone exchange ySvStpni ol this particular' charaOtCr. f

To the foregoing'and other useful ends,

my invention nomini4 iti nuittoi lii'oiu'itttr 55 sot: forth and claim@ Figures l, i? qno" 3 tuk-nn togothr rvpro- Sent tho circuloy and sivitrh im owfi whfn a subscriber at on(l rxffhaugo (Vig. l) walls a suhsvrihtr at fronti nii-hanno (Figs. 3 G0 and 3) over a t,v\'o\va.\' trunk oinhoiivinif thi prilmiplos ol' nl v invention. ln Fifi. i tho (falling SuhStation X i-y shovrn ronuoftwJi to .i tirst-Sclootor loiatwi it tlm rntfal i.\; I Chango #1, said tirst-ijlof'tfjr twin; nllottoii G5 to .Saul line. The #am mitch loo: nonlai Conufefftion with tit-' f'ontrfil im, l of thv contra] ottico jpl. 'To ilu iight L" 1 lfffltor A an impr-rivoli rrpnafr t' portant part in tho oyorfttiini o' 70 l To the rijfht ot will rvprator i ot' the iiuprovoii similmswitvhes l) uhu-h in of tht .uw i to whirh tho sflrutor fr. tot or l roptatm' (l :unl tho improving? wir .7

i i l l l i I f i i l i i i i l nent vontral with wni'ral ft' allottuil to one o? tho {ruoli-l' switvh l), from thi thu ffvstrni, is humm ln Figi. i? t rcpriffwnt tlm l chang@ #2 allottml if fhv anil tho aiowiatmi wlw-tur l th(l right ot" saiil rfpffatvr t amt t" and tlw l uw hiuiilar, lu l ff ll i' zillfittml to l'lu" right of saifl Coni. vwlw-tor 1 allott-f lilt, Thu ,Cfiiii Lvfii'ofoi 1.1 .i to tho first-:wlwtov lu Swirl iriol 30 alloil #ulistatiou jfl' '1 if; atar'. \.h-' i\.v:;. aiul ia, Ot' rouw@ foziuw'f'wl ith ailotfal first iloftor 1. Fig. i is` n ..imniativ porn pt-live vioiv of tho liet-wiwi Figa. :3 arul (3 nro umilar vioxw of thi" improved si 95 loitor Dl uur! vounofior ll. i .f-:iuwiivtlv, Figi.. 7 its a siuipliiml iliagfraiumatio drawing showing tho nirruit@ through whiz-h ilu; talk ing' hurl-notie aiul tho Voir@ vuriintu aro goilthlctfrl ivhOn tivo nhsvrihoiw aro Connor-tml.. No At, tho substation.m th( soroiularv iriniliu'ga alul thoir rtvciwrs iz: serios withlsaaiil vviiulings are not shown.

The sul'iscrihcr at Suhstation X, in 0S- tahlishing conneition with tho Sul'icrihcr 105 #2220. operato# his dial sh osv'n) four digit ot' thc ing his dial for the first digit the first-l selector A raises the line and private wipers of the switch-shaft to the second level of their banks and rotates them into connection with' an; idle trunk-line leading, for example, to the repeater C. The wipers might have stopped in connection with some other trunleline leading to some other rcpeater similar to the repeater C; but as soon as the connection is established with the repeater C a guarding potential is established by the first-selector A at all bank multiples by which the repeater C may be seized. The same guarding potential causes the vertical switching relay a, of the repeater C to be energized and to perform, among others, three operations. First, the vertical trunk-conductor b that connects the two exchanges is disconnected from the vertical line relay c of the second-selector D. Second, the said vertical trunk-conductor b between the two exchanges is connected to ground by the said relay a. Third, at the same time the rotary switching relay d is also pulled up. The said rotary switching relay (l at once cuts oil the said ground connection to the vertical trunk-conductor b. Since the energizing of the rotary switching relay d follows close upon the encrgization of the vertical switching relay a, the ground impulse given to the aforesaid vertical trunk-conductor Z) is quite short or momentary in character. Not only does the rotary switching relay d cut oli the ground from the said vertical trunk-conductor I), but at the same time it disconnects the rotary trunk-conductor e of the trunk-line connecting the two exchanges from the rotary line relay f of the second-selector d. The said ground impulse delivered to the vertical trunk-conductor b passes through the repeater C1 of the second exchange Without operating said repeater, and energizes the vertical line relay g of the second-selector D1. Said vertical line relay g then causes the vertical magnet h to attract its armature 27, which latter draws the release-link y' from the double-dog c, whereby the latter causes the spring l to engage the ground contact m, thereby placing a guarding potential at all multiple terminals n of the repeater C1 to prevent any selectors of the second exchange from seizing said repeater' C1 in the same manner that the lirst-selector A seized the repeater C. It will be noticed by referring to Fig. 5 that while the double-dog k is retained in normal position by the releaselink j the pawl o is prevented from engaging the circular teeth p; but as soon as the double-dog lc is released, as described, then the said pawl 0 is adapted to raise the shaft of the switch D1. The subscriber having thus seized and appropriated to his use the trunk-line leading A*from the repeater C thc-n operates his dial for the second digit.

second-selector D1 is then operated to raise the switch-shaft wipers to the second level of the switch-bank and to rotate the said wipers into engagement with an idle trunk leading to the connector E. As soon as the said trunk-line is seized it is, of course, protected by a guarding potential to prevent any other switch from connecting with the said connector E, for the time being. The subscriber then operates his dial for the third digit, whereby the shaft of the connector is raised to the second level. Then again the subscriber operates his dial for the last digit and rotates the said connectorshaft so that the line wipers are carried into engagement with the contacts or terminals of the line-conductors of the desired subscriber. n

ln detail the apparatus is constructed as follows: The subscribers station may be of any suitable, known or approved type. Said substation is provided with a wellknown impulse-wheel 2 which has the usual vertical impulse teeth 3 that are adapted to operate the vertical impulse spring -l in such a manner that the said spring may be pressed intermittently against the ground post 5 for the purpose of sending' jround impulses to the vertical lilie-conductor of the subscribel"s line. lhirthvrmorc, the said impulse-wheel carries a rotary impulse finger (3 which` after the vertical impulses are sent, acts upon the rotary impulse spring 7 so that one ground impulse is sent to the rotary side of the subscribefs line. 'll`he substation is, of course, provided with a suitable switch-hook 8. Said switch-hook has a number of cam-arms 9, l0 and 1l. for controlling certain operations and circuits of the substation. rl`he'ca1n-arm llcontrols the so-called locking arm l2 in such a inanner that when the switch-hook rises, and before the dial (which is not shown) is rotated, the insulating tip 13 upon the end of the locking cani li) that normally rests in a position shonn at substation #2220 is driven to the inner oi' the angled tion prcfvided at the end of the so-called ground spring 14, whereby when the dial is pulled down by the calling subscriber the pin l5 upon the end of the locking dog lo is able to pass beneath the said locking cam to raise the said cam a little, causing the said insulating tip 13 to fall. behind' the said angled'section of the ground spring 14, permitting said spring, therefore, to make' electric contact with a coperating ground spring 17, The engagement of the said ground springs ll and 17,' upon the operation described, places the ground post 5 in connection with the substation ground,

rwherein] when the subscriber releases the arihed, the ct upon l an riant urns: lw sillwrrllwfs limx wvlmn 111km nullhowl; rs. (lawn. ir. #vries im :l (rundexlrzor 24. lVllu'xr thv .Hwtvll lmuk down, Stated. lle rum-arm l() nmlmnin@ ll'mswtclr spring tari e the Qircular teeth "t" one Step at a time. vertieal arin 1137 the red by the L-shaped !iire vonilut-tor im i.` grounded the roline relay 17T ot' the 1ir=t-feelevtor is enl and thty rmid relay then ranges the magnet, [itl to be nian'netizt-l tor opiiig; ila ide wt'itf'h ll. The energizing ai its tor tlxr rotary lint` relay Yt? may be time it trito the -ulf-tation ground t?! to the tlwnt'ttu'ouo'li the rotarV to tin' rota *lne conductor ,vontat-t-iiouit l'rl.

:Mary lint relai' 1T. bridge- Yorina 1141. 1:33 and 1go to the 4-il and through hattenY l5 to lr ;f|"\` y ine it' then li :Uitl llieteittj lires Lil) V" I o iii will the f "rotntl tiring loo. iles` rit fai-:int wil then llow troni .tw'izntt ii* t, 'tjyfi he brings 14.1K; and 1T",

Iiff'-5ofl t and 1TH to the private triagt ttt lluftite to tlitbattery l-tatl ltil) :Uitl i to giou'od (i.

the liwt nine wontaf-ta ot `l ol' tiniiriifatt haiti( l-l are' `tot. that the tiwt nine trunk,` to wi et' tinline bank t2 are in =jgjuet 3() by operat- 1"l eat.. .1 the title .awitth mi i o-ition :in energizing" tbliehefl through the rotary i7, to naar the ;-l|at't one step. At

WJ; 'lttittiil :it the first toiitat't of the )tritate bank 'l. so that y uws-.et .W i-1afgziiu energized for ing the fiile switt'h in set'oiul position until tliz rotary magnet l1-1 has ea-rried the einer past all buny trunlt'r'linea. 'l`lie pri- \.'ate iiiagi'iety unen bewoniinn energized, aS tlezwrilietl. attrtutr thtl private armature 180,

tote! ttl" 35 whereby the ewapement-tootli 1551 flears the wwaiwinetttdinner 152. :intl the t'etr:u:tin; laine 23 :alrnuetst the oseapeinent-finger 1W affari-t, the aimer rearinost estal'ienient- @with 1 When tot privat armatore retJ torn to normal liostition the esrapenienb linger 1*2 vlnr# in turn the tooth 1ML and the li 1 the lira-e o1 the finger 1.*52

i .31 and rrtaioe the naid estilt-tern the teeth 1551 ,fourbe it will be underatood.

ythat the. retraeting-spring 183 provides the torce that continually advanees the side Eswiteh from one position to another during the eall. lVhen the Side switch passes to set'ond position the side Switch wiper 187 70 `engaggfes the grounded contaet N8, whereby an energizinw eirtfuit tor the rotary magnet 4 Vis established. The current in this circuit passes from ground G* to the contact-point- 150%. tht-nre to the side Switeh Wiper 1ST, eon- 75 duetor 189, to one ot' the Coils 190 of the rotary magnet 44, thence through the Spring 191 and 192 and through the other coil 193 'ot the rotary magnet to the battery lead 160 and through battery B to `freund G. The go rotary magnet upon attracting the rotary arlnature 19t rotates the shaft 37 one step so that the private wiper 40 engages the tiret Contact of the second level of the pi vate bank 43. l`he said -eontact being,y 35 Aroumlml the private magnet 5() is energized 2again, as t'ollowa: from the ground terniinal (r ot battery l) and through an oeeupying ,-,\\it, h and bank inultipling conductors to `the first rontatty ot the :ferond level of the 90 private haiuk 421, thence to the private wiper i0 eondut tor 195, haelt-release relay '19, oondut'tor ltlti to the side Switch wiper 1f", thenee to the eontart-point 198, conduetors 190 and 1711 to the private magnet 50, thence 95 yto the battery lead 1GO and through battery l to `ground (l. The private magnet then atti-arts its armature 1S() and loels the esft-apeinent-linger behind the tooth 200.

leaves the lug; 185. The side Switch being thu loelzed in Set-,ond position the rotary' `magnet t1 is energized intermittently as long' as the private wiper "10 tinds busy c0nrate hank 43. As a rezliult the rotary armat- `ture 1971 ist attraeted and the Shaft is rotatted IQtepliystep until the wipers are carried into engagement with the tenth trunk-line stated, is the only trunk-lino on Said level that ia idle. At the instanty that the private wiper Lt0 leaves the last busy Contact the energizirngf eireuit through the private magpasses to third position and the eseapeinentfinger 182 falls against the side Switch stop :201. The side switch wifiers 154 and 173 rthen engage the oontart-points 202 and 203 eontattpoint i204. lThe side switeh wipers 151 and 1723 thus extend the subseribeids line eontluetow 152 and 153 by way o1' tlle eondnetors Q05 and 20G and line wipers 3S and and i208, as yahown in Fig. 1.

The engagement between the Side Switch wiper 197 and ontattpoint 9,04-, as de rteribetl.y plat-ea a guarding potential at the tenth contant ot the second level of the m This. of ourse` oteurs before the :am 51 100 tart-points along the ete/fond lovel`ot the pri` 105 `tot' the fte/eend level, which, as has been -110 `net 50 is destroyed and the side switt'h II 11s @and the side Switch Wiper 197 engages the 120 39. ;e:-peetively7 to the tritrilt-conductors Q07 125 private bank 43.' r1`he connection between said contact and ground is as follows: from ground G5 to the contact-'point 204, thence to the side switch Wiper 197 and through the back-rclease-relay 49 to the private wiper 40 and to the said contact. The seized trunleconductors 207 and 20S are thus protected from seizure by other first-selectors 'which have niultipled contacts at the said seized trunk. At the instantthat the said guarding potential is established at the said tenth contact of the second level the vertical switching relay a of the repeater C is energized. Said relay receives current from the irst-selector A from the ground G5 to the private WiperdO, thence to the trunkrelease-conductor 209, ,conductor 210, second-selector springs ll and 134% conductor 211 to the vertical switching relay a, thence to the battery lead 160 and through battery B to ground G. It will be observed that this circuit includes the relay 49 of the first-selector A, but the relay a is of such high resistance as compared with the relay 49 that sufficient current does not flowto operate the relay 49. The switching relay a alone operates. The said relay upon becomingr energized presses the springs 112, 113 and 114 into Contact, and as a result two operations are simultaneously accomplished, natncly: A ground connection is established to the vertical trlink-conductor and an energizingj current sent through the rotary switching .relay d. The circuit by which the said ground connection. is established may be traced from ground Gya to the springs 112, 11S and 114-. thence through the springs 119 and 11S of the rotary switching relay UZ and to the vertical trank-conductor ZJ. The energizing circuit through the rotary switching relay al extends from the same ground G" through the springs ll and 113 and to the said relay al, thence to the battery lea-'l 160 and through lilattery B to ground G. As soon the said relay becomes energized it attracts its armature and thereby separates the springs 118 and 119 so that the ground circuit to the vertical trunk-con luctor b, described, is at once interruiilted. The said momentary and preliminary ground impulse to the vertical trunk conductor causes the verticalmagnet L of the selectorswitch D1 at the second exchange to be enu ergized sutlciently to disengage its releaselink j from the doubledog lug 212, but not srdliciently to canse the shaft 138 of said switch to 'ee raised. The said release-link being disengaged, as described. the armature 2115 of the release-magnet 214 is then 'Withdrawn fartherfroln the core of the releasemagnet by the retraotingsprng 135, and as a result the spring l engages the ground spring m and establishes a guarding potential overthe trunk-leienssa-conductor 215 to all trstselector private bank contacts n that 'are inultipled to said trunk-release-conductor. Therefore, the seized trunk is not only protected from seizure at theirst central conductor and the said trunk-conductor is connected instead with the Winding 9() of the repeatingcoil 88. The normal connection with the said vertical trunleconductor Z) is as follows: from said relay c over the conductor 216 to the contact-point 217, side switch Wiper 218conductor 219, through the vertical switching relays-prings 115 and 116 to the said vertical trunk-conductor b.

The connection between the vertical trunleconductor and the Winding 90 of the repeating-coil is established, as shown in Fig. 1, through the springs 116 and 117 of the vertical switching relay a. Furthermore, when the rotary switching relay d is energized the rotary line relay f of the selector l), in a similar manner, is changed from normal connection with the rotary trunk-conductor e, and the said trunkeonductor is connected instead with the winding 92 of the repeating-coil 89. The normal. connection between the ,rotary .line relay f and the said `outgoingr rotary trunkfcondoctor e may be traced from the said relay f to the conductor 220, contactpoint i221, side switch ,wiper 222, conductor 223 and springs 122 and 121 of the rotary switching relay d to the said rotary trunlrconductor c. The temporary circuit between the said rotary trunk-eomluctor e and the winding 92 of the repeating-coil 8S) is established through the spring-:s 121 and 120 of the rotary switching relay d. Therefore, When the two switching relays a and d are energized the vertical and rotary line relays c and 7 of the selector D ai e cut oil' from the trunk-lineconductors and e, and instead the said conductors are connected through the windings 9() and 92 of the repeating coils 88 and 89, respectively', and'through the condenser 94. Therefore, by the first operation of the dial the calling subscriber at. the substation X establishes lconnection with the repeater C and sets up a guardingV potential to prevent anyone else from establishing,` connection With said repeater, which guarding potential also energizes, first, the vertical switching relay a and, sec ond, the rotary switching relay d, thereby sending a ground impulseo'ver the Vertical trunk-conductor"6" to o crate the vertical Amagnet L of the secon selector D1 at the tit) that lmils 'imm lh@- rwliifim' l). ''l up ot' thil relays a mill f/ li rolzi; f' l f ws'. hi wliiim trunk-inw :imi 'lww: i cinnliiwifwx milling' sails: ur thaw im mtv his `lixl br .1. ing; gis liiliirc. the vili-tical 1,32 twicv :unl thf ru lim-ww mmh lfzlch (imix that thv wr (,lllctnr L32 if gji'oiihilwl thi in" luy 8l ot' thv rvgwutvr t" :mi iwilill rcluyi Si are iiiirgzj' :wlA ll hw limi in the energiz/,ingg in'ulril ffiww t'; (l2 to the veu-tival trim!k mi if; when the Wrtirnl im'mlMl mitad, and thm www; m wiper 154- of thvy tir# point 2012, conductor t 38, vvx'tiifil trunl; lineJ relay Sii mimi y relay 82 to the lnittury l'wl i'i" lmttry l in fxoiimi t, Sti is in shrill with \litlivrilh,ii thxj: :spriirw i vll-:infin 'incr i Uit@ this( mi l'hmz the:

vom

:will im iti mi' Ll 'viriifrril trunk-- grmmfinrs: the .will trzinh-uunllxiit'iw /11 @mnh timel tha the ffz'riiimlml will wrliml liml comizi-"tm" l he itlvfsurihiil. lty `will hv imtmwl lit, uw the gmini-il viii-:lit lwtwuch thv frumil thi'- minnl (1?" :mil thu wrtiml frm:lvvmiihifftor /1 i'oilxpx'isia; fliprinfLs vmitirolhil lq' the will rhilugfimr-rvlziy 53 it, tihzlt the will fifliiy H3 shimlil not; h@ mieri'izeil hihthil wrtimil imlnxlws .lusired :1re transmitted. lt tho ilill'vrcntizilrelay 32 :ahuulil mit pm-:itu the springs ltlil :intl 103, :is :ih'wuly Stiitifil. it ie pmsihlfs that the relay' 83 might homme mim'jguiml (wmf the fol lowing (zii-ruit, .rlwn thfxlsnhl springs 1U() nml Sli* :iro prvwml iztr) esimurt iff.' rhoy ver tival line relay t5 from ILmiinlft il? through thi Springs: it?? :mil 100, :is hit'm'. tl thruiilfh thv spi-ings lt-T' :zml :im

.w rm'ny H :mil Sprit .iilnjg Sil wrt :mil f .mining L il Pim milisiing they the release-h liti ` to the private magnet 246, thence to the battery lead Q31 and 'through battery B1 to ground G1.

lVhen the. private magnet attracts and releases its armature 147 the side switch clears the escapeinent-teeth 219 and '250 and is drawn into second position by the retraeting-spring '252. The lug 253 then strikes the cam 254 and retains the linger thereby energizes the vertical magnet ,71. The current 'in this new circuit lows from ground G8 through the springs 233 and 232, conductor '234, private springs and Q36 to the vertical magnet h, thence tb the battery lead i231 and through battery B1 to ground G1. The said vertical magnet then operates the vertical armature i, previously stated, to release the doubledog le,

whereby 'the springs l and m .may come into 251 between the teeth Z55 and Q49. lVhen the 75 Contact. As soon as the said springs engage said side switch l passes to second position. a connection is established between ground the side switch Wiper 256 engages the con G3 and the private conductor Q15, as previtact 257, whereby an energizing circuit ously stated. The two ground impulses dethrough the rotary magnet 141 is Set up. lhered to the vertical trunk-conductor b The current in this circuit flows from 80 from the ground G7 by the vertical line reground G10 through the contact-point 257 lay S1 of the repeater C causes the vertical and side switch Wiper Q56, conductor Q58, line relay g of the selector D1 to be enerrotary magnet coil 259, interru )ter springs gized twice. The circuit beginning Wit 149 and 150, rotary magnet coi 260 to the ground G7 passes through the springs 109 battery lead 231 and through battery '1 to 85 and 108 of the pole-cbanging-relay 83, the ground G1. Assuming the first nine consprings 99 and 100 of the line relay 84, taets of the second level of the line bank 240 thence to the springs 107 and 106 of the poleare busy the first nine conta/ets of the secehangingrelay 83 and springs 117 and 116 ond level or' the private bank Q41 Will be of the 'vertical switching relay a to the vergrounded for Well-lmovvn reasons. There 90 tival trunleeonductor Z), thence to the springs fore, when the rotary magnet 141 operates r and y to the side switch wiper 228 of the to rotate the private wiper 239 onto the rst seleetur D, eontaet-point 229, conductor Q30 contact of the second level of the private and vertical line relay g to the battery lead bank 241 the private magnet 246 will be i231 and through battery B'L to ground G1. energized (as described in connection'with 95 Said relayy, as already described, each time the first selector A) for locking the side that it is energized, presses the' springs 282 si'vitch I in second position to maintain the and 2513 into mmtact, whereby the vertical energizing circuit throu h the rotary magmagnet /z energized each time. Being ennet 141 until the line Wipers'l and 238 l ergizell twice the said vertical magnet atl are carried into engagement With the eon- 100 tracts its armature i and causes the pawl 0 to ductors 261 and 262 that lead from the tenth the .zircnlar teeth o, sinee the pin 127 contact of the second level of the line bank den.. lealog ,if new out of the, u'ay 240; and the private Wiper '239 is thereby oeh :it the paivl o, thereby raisrotated into engagement with the trunk-reshaft 138 tivo steps. The lh" wipers lease-conductor 263 that leads from the tenth 105 and 23S and the private wiper are 't of the second level of the private to the remind level of their respective y bank 211. As soon as connection is estab- BAO and i211 and le ready 'lo be rol lished with the trunk the side switch I cement n 'li the. eontaets el' i n te third p""tion and the side switch han idlii-,n the rotary l \v andia ethe contact-points vl1' lutter e is g inded by the opera .e r and i163, whereby t le trnnkronduetors he rotary line relay 85 the rotary l o and are connected, respectively, With the lnerelay 1223 of lhe selector D1 is then ener l, trimlt-eonductors 261 and 262. The congized. The fiiwrentfor energiz/.ing said relay l meeting circuits are as follovvs: 'lhe vertical 123 hows l'rem ground G7 through the trunloconduetor l; and the vertical trunk- 115 springs,- 109 and 108 of the poleehangingconductor 261 are connected through'the relay 8f3, thence through the springs J8 and springs q and 11, conductor s, side switch GE) ot the line relay S5 to the conductor 5227, wiper contact-point 2611, conductor ,260 thence tl'irough the springs 120 and 121 of and vertical line Wiper 237. .The rotary the red-arrsii'itehing relay al to the rotary trunk-conductors e and are connected 120 trui eenriduetor e, springs fi and a', conducthrough the springs t and u, conductor lv, tor yz. side ewitcl'r Hiper 2, contaetpoint side switch wiper 212, contact-point Q05, .Jll. conductor 214, rotary line relay to conductor 267 and rotary line Wiper 238'. the halter-v lead :231 and through battery B1 When the side switch Wiper Q68 meets the:- io groei/if "11. The rotary line relay 123 eontaet-point Q69 a guarding potential is '125 upon' attracting its armature forces the established at the tenth contact of the se@ springsd and into contact, rwhereby ond level of the private bank r2111, from the, riya1e magnet 240 is magnetized. T he ground G to the eollitac'tpolnt 2369, thence eurrent passes from ground GS through the through the side switch Wiper 268, baek- 130 springs Q33 and 2&5, conductors i217 and release-relay :270, conductor 271 and private 1 1oz-mau wiper 239 to thls Suhl wiffnlgact, After the zvaflisnril'tr has` nstahliulmfl (winnt-stima with the wnnmtor ,li bj; way nl' the? trunk-corr ductoru 261 and as ilcsrliilwf, he open ates his dial for the :QQ/wml digiti Again the wrtiilal lino cornluuthr '1.72 'la grounded twice and the rotary lino Constantin' L33 onro. As a rhult of grounding tlnl tornwr the vertital tina relay T5 of the connector l und the? elill'nrvntir-,t rvlay 'Ti' are i-nargizesd in a smiles cirnuit, llach tina: that thivrvcrtiral: lino fuiuluctor L32 is; grotuulml. hun the ilnpulxo Spring l operatnrl, tl, i'vrtical lino and llil'erontial relai/,s Si und h2, respoetivcly, of the repeater t] are energized, aS in previous; intances, so 'that the vertical trnnlf-vonllurtor is gronntlwl nach time, also causing a flow of current through said verticu` line and differential relays 'T5 and TT of the connector E. The Current flows to the vertical trunk-condnctor o, as heretofore, from ground Gl at th@l ropoatnr uml through thev wrngii :lll and 10U to the Quid tranli-wnxlnrtor h, thrift-u thrfaxg'h spring y uml lf' ot' the greater t" to the Maul rtor Side airitvh 'a'ipefr 152k. fr-niark point Zul. "fnnlnctor i566. tri-tival' hun wiper Il?, Wrtical trunk-wrrnluctor itil, 'mxrfinal line relay T, whirling "E nl' tlnA differential relaja T? to the hatten tuali L25?, ami thruunh battery B1 to ground G1. sl/han thv vert `l line relay T5 is Qnergizml tinA lira; rfJ-lay spring 273 i; pr ml unto the grfmnd spring 274-, and as; a result the vm ital ma@ not T2: if Qnarg'i'zed. Thr circuit' Qatahlislnal xtornls fl `:in 1 rouml (il: tln'ouffl'l thvy springs QU and :473, xnnhirtor 2??) to the privato spring; To am! 2T?, roaflurtur 278, ahh: awitrh u'ipnr 27S'. colatalztpoiut 9530 to tlmy tefrtiral niaglnat T2, thermo to thv liattiry leall .381 and through battery Bl to ground (il. The cnergir/,atifm of the tlitl'erential rn" lay 77 han no signilcanvn at this time, hut the operation of the vortal magnet T2, sine@ the Vertical limk relay T is nncrgzizctl twice, cannon the shaft tn ha raiScd two stops anll the line wipers Ct) and (l nul tho privato wipnr GQ to lm plavml oppnsitn the trut Contact, of the sccond inw! of their respnctiw lim` and` privato hunks G8 and 64.

lVhon the rotary lino condlutor 153 is grounded the rotary and differential relays Si nml 8:? of tihn rnpoatfr (fl are also enor gizcd, as prnviouslj' dosrrihed, wherolrv th@4 rotan,Y trunk-conduutor r is grounded anrl the rotary line relay 7G and (litl'orfntial rolay nt' the fainnwtor aro rnvrgiI/ml, The rurrnnl through ,said lino :unl 1lil'ornntt-l rniaw Tt? and 7T flows; a# h; from grminfl (2" to the @,-rimgfs Sli" rotatif; line? rvlay to tlin r ductor r. tlnnfo through tlm lu" thv inheritor (fl to th or to tlit SiilB Dl, Contact A that loa@ jnntlxrfil thv line raluy spring 52H5 Y .into he g'roural spring :27%, their thv/privat@ anagnct Til tor .Lfuitrh l from libri to nel i 'iinfffircuit through private? rnugnvt 7i is ,vs tfolloa from ifi-ouml tl" through thi Springs [il anu= 295i, nontluvtnr ifSt, privato magnet 79, ctiunluctolx l ansrl S2825 iolv-fhanghng-rvlay Springe? mul .QS-l, to the hattnry l'atl 231 anal throug'i'z hattmfy Bl 'to ground (ille, The pr'vatnhiagnnt. Tf) is thus energized nnannni' tarily. and the privato armature i258 is at,- .tractd and released, whereby they escapel'nenttlnger Q39 chairs the eSCapnnientrtevth 290 :unl 259i, no that th(l sido xa/witth l is drawn into Inroxnl punition by the retrafztmgb Hiring' .lff. li'hvu un sida :mitrh pawns tiax fwntartpnint l inutead, hr1-@hy the elet izing giri-nit through thtL w-rtifal magnnt T2 i@ iunrriuitwl unil eutuhliahml through utary ma not. TS inutmnl. 'l`ln1 sul rihor ilu-u op ates his: flial for tho last digit' ti. cnfgratheg the iinpnlun spring -l to frontal tl g wriral linfa rontlurtor lim ten firmasx :unl 'nwrating the rotar)v unpnlsf spring T thereafter for grounding tht, wtary lino roudnrtm 153 once. The vertical line rnlajv S-l of ihn repater encrg'izictl ten tizuw` over vire'uits that have heen trafwl la tor llorolrt tlul Vertita'l trunk vnln'lul'tur (D is grouinlmlnn tintos through the ground GT, and Whrrnhy thu vertical line relay T5 of tinl rnnncrtor E energized ten timos, as proviouhly lhboribor. However. when tho Said rnlay prensas the springs i373 and 274 into Contact' tha crtuit that is coniplntetl extends through they rotary magnet 73 iu- ,wtnarl at through thev Vorthial magnot 72. The virwut may he tratml from ground (lf ovni" thv sani@ path described in the last in stuurt, as fur as tho Sido switch Wiper Q79, and thelne it extends through the Contactpoint 293 to theI rotarv magnet 73, battery lead :231, and from battery B1 to l@round (il. Each time that th@ rotary magnetl 73 is niagnotizetl thvy rotar)7 arniature 294v is attracted am that they pawl i295. hy engaging the longitudinal tooth (Sti` rotatos the Shaft 59, Carrying` thry thal wipers (it) and (il into @ngagemont; luth thv trxuilt-ruxnluntfa's 291'? and 1297 A l l "rivm tho tenth terminal ot' they ser llw'ul iulnehainh t3 aznl tht privata "mnfnt with the privato ulmrm 'Q hai-fling; from the tnnth the @femml level of the private 1 (il t' bank (lil (lroaruling the rotary line con n entra wat@ magna?. A) s that h vgmpmmm imgvr 302, Side wma@ pmu. 2101',

E gummi (31". .w

up hun;

-The current door. not reach there direct hut .im olmo presses his signaling button. ais '.irsilrihed, i' vertical friiiil;

thereby grounding the vertical iiiic condor l wid spring ffii :mi tor LM', the vertical line rohiy '75 is energized l siilii through ihr ri -ii so thar, slice the :side swilh J iiow iii first. s Niniki-mulini or i position, the vertical magnet: T2 raises tho switch-shaft 59. The sirilili-sha't springt?! 341 and than close hito Contact und :i 'usy signaling current i5 rrunsniittoii i'roiii the biy coil to the siibbcribefs Station.

lli" Mil oi' armeni.'

,in the ollowiii i' iriiiiiiier: The flow of current s first established from the ooil 343 through the Springs 34 l :imi Hi-"f lio the .side switch sur ta/Upoint 344, thficc through ihry i@ido switch Wiper 310, ringer-relay spriiig 309 and 308, conductor 30T, coi'ideiiser 30H, rotary trunk-conductor 262, rotary lin@l iviiior 2238 o* the selector D1, roiitacbpoiiit 2153, side switch Wiper 242, rotary trui:lc-rzonrliirio: if,

relay 3"* lily :Springs Q iiifz trim.

z'pezitor roiury siif'itchiiig rainy .-}i1iii 'u conductor 195, private wiper A10, thence 55 sind` I?, rotary trunk-Conductor c, roiiiiiier ilirougli iii@ im@ ri-.iiiy springt, lill iid 9T, rotura1 Switching' relay Sprii. fs lil zuil 12o, ro iiiiicrfifoil {iii} dilii-.i'iriitizil mirri; springs ings ill and 93, passing tiiiiire i'roiii tho siiirl groiiiiilrrl ifi thu fiiiiiriilioii of th@y luid re- 100 windings over the heavy conductors shown y lriisi: iii-ing@ 3l. 35 iiiiii i iii '.l'lig. l, through thrpriiiiziiffY iiiiidiiig 2O with iiirlhir rci'i'ioiioro ihr A iiiiiiliiiiioof the iuliicioii-coil 1S? it thv willing station. M" ii'i'oiiiiiliiig; of 1hr, .ifririil :mil ,roiiiri' A current is iii torri iiiirliiiorl in the soroiiihisvi' iriiiiivroiiiliir!ors :iiiil r. il vil! life omi tliii'f 'l olA the iiidiirlioiicoil if) whiifh iii ifiirrgiziiig ifiirroizhy :iro i-iilfl iliioiiiili .iivi

windin f turn ulivo-is the rccuivcr Thr: ifuhrrihrfr tiir i'ifriiriil iiiiil riiiiiry limi rrhii' 'Jf iiifl Ti upon hearing the liiis igual riiiiioros his rr i' oi ilu: ioiiiirrior ii. oirr 1li ii iiiiiy ho i'riirml from groiiiifl (i2 iiiil through iiiiorro oiifh otlili' iii mn g Hihi rrtho ground springs i4 imi l to the ruinoso ,hija ifhu :iiiiiiltriiiooiiff` riwi'gr/.iiig if ihspring 34, thence through tlwy springs 3f mil sziid liiivy iiiiil rliilirf-iiiil rflliim roiiiliiliftrs iiii 'Hf 3G to thr, rorspective coiirliirftori.` 1.5L und 152i. l energizing cirriiii. i'hi'oii the ir'lriisrf-iiiiiif Current will flow through the vertical zuid rior 'T4 of the rroiiiicri'or, iii serio. ith th@ rotary line--roliiys 84l and 85 of the repoiilrr izirlerolriim-rrhii 2T() of rh@ wlrrtor DI. C and through rho windings' SG und 8 of the Thi.4 virriiii il i iiiiii li^r l hi; ihr Ziriiiffilifferr-zitiul rohiy simliltsiiicoiisly. V`l'liiiiiiigf imo roiii'iu'l oi the triiiilvi'xtiozislr l'f .siiirl lino rohrVS 9L :iiill 85 will liu riwrgizwl l siiii bai 7248 :imi iii?? iii iho iiiw rrliiiw T3 together with the liil'oi'oiitiiil rrhr'v i :iiid Ti :il ihr :sioui'iiiir ihii thv rliii'rii-ii i l i Wiirii siiiil lili@r relays :imi 8.3 profis flug iiiil rrlny siii-ini` mul fli :iris iii cori- Siiriiitgs fm. $15) :zuil 10U Mito riiiiiiir.. (lio wri ffl. logiiiiiiiij vfih ihf, l lifriiiiiiiil ire groiiiiilrii siniiiltziiiiiiiisy rom I,groiiiiii' the i'ii'roii' ci. i: point (1" through the polc-nliiiiigiiigfiehiv springs f @wir {mi-inqui.; A m.

1.09 and OS to the ground spi .iigr fifi. ihsfiir r. o`r privato ii" mr i truiilvrolefisothrough the spring 1.00 mi one y A J ir/mid pole i conductor :363. triiiilvrelwirwos iriiig S4- :imi .o r v "5' J nu 'i l y ohaiigiiignehiir pririgs lo. and 106 to (iii). l 345), i'feloiise-riiiigiiot rfi, ihfereziiizil rehiv 130 

